I believe that encounter traps are just one manifestation of an important 4e design philosophy, namely:
All PCs should be able to contribute in all scenarios.
It doesn't mean that all PCs need to contribute equally in all scenarios, or in the same way. However, I believe that 4e will avoid scenarios in which one or two PCs do all the work.
So, instead of simply having the rogue (and only the rogue) disarm the trap, the rogue disables four mechanisms and shuts down the main trap, the fighter smashes two, and holds back the wall with spikes for a round, and the wizard burns another mechanism with one spell and suppresses the effect of some mysterious glowing runes with another.